As well-known, in the shoe industry fields, a method for manufacturing uppers of shoes using a hot melt film with no sewing has been widely used, and recently, various materials as ornaments for the uppers of shoes have been used.
Recently, skin materials made of polyvinyl chloride resin or polyurethane resin which are bonded with fabric have been widely used as the uppers of shoes. As an example, a technology of bonding fabric for the uppers of shoes to the top layer of a polyurethane film using a high-frequency fusing method after printing by a comma coater method, a screening method or a copying method has been widely used.
As described above, according to the conventional method, the uppers of shoes are manufactured through the no-sewing process. As materials for the uppers of shoes, as shown in FIG. 1, a polyurethane skin with colors is coated or a thermoplastic polyurethane (TPU) film 20 (hereinafter, called “TPU film 20”) with colors is coextruded on a hot melt film 30 made of thermoplastic polyurethane so as to form a skin film 10 having at least two layers.
In order to use the skin film 10 as the uppers of shoes, the skin film 10 is put on a fabric material 40 which a user wants to bond, and then, is bonded to the fabric material 40 when the thermoplastic polyurethane hot melt film 30 which is the bottom surface of the skin film 10 melts by heat and pressure through the general heat press work, but the TPU film 20 with colors which is coated on the hot melt film 30 does not melt so as to decorate the uppers of shoes.
However, the conventional skin film 10 for the uppers of shoes cause color transfer that colors of the fabric material 40 are transferred to the skin film 10. In detail, as shown in FIG. 2, when the skin film 10 is bonded to the fabric material 40 through the no-sewing process, dyes (red dye in FIG. 2) used to dye the fabric material 40 change the color of the skin film 10, into orange color in FIG. 2, while being transferred toward the skin film 10 during heat press work. Therefore, the conventional skin film has several disadvantages in that bright colors cannot used, there are many limitations in selection of colors, and the color of the fabric material 40 is transferred toward the skin film 10 when the user uses the shoes for a long term so as to defile the appearance of the shoes.